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Grass, grass & more grass

Graeme Finlayson (Ecologist)
Published 18 Feb 2022 
about  Bon Bon Station Reserve  

Fields of grass have appeared following the rains. Photo by Graeme Finlayson<br/> Fields of grass have appeared following the rains. Photo by Graeme Finlayson
Gosse's Track became a swamp, with Nardoo water ferns! Photo by Graeme Finlayson<br/> Gosse's Track became a swamp, with Nardoo water ferns! Photo by Graeme Finlayson
New lakes have appeared among the chenopod shrublands. Photo by Graeme Finlayson<br/> New lakes have appeared among the chenopod shrublands. Photo by Graeme Finlayson
Plumed Whistling Ducks have arrive. We hope they will nest. Photo by Saskia Gerhardy<br/> Plumed Whistling Ducks have arrive. We hope they will nest. Photo by Saskia Gerhardy

My first trip to Bon Bon Reserve was in early 2018. My first impression was that it was very dry, albeit still looking in much better condition compared to some of the surrounding landscapes. And the sunsets… just wow!

I was in awe of the size of the reserve – at just over 2000 km2, its one of Bush Heritage’s bigger properties and about the size of the Sydney basin! Having had no stock for a decade, and no free water for attracting other grazing species such as kangaroos, even during extended periods of drought over 2018‑19 there was groundcover, holding the soil in place and building resilience.

While dust storms became a regular occurrence across much of the rangelands – with soil even turning up on the snow-capped slopes of Mt Cook – Bon Bon seemed to ride it out. Slowly, cryptogams are replacing heavily impacted bare soil and perennial grasses are coming back.

A total of just 41mm of rain fell in 2019 – most of us experience that sort of rain in a few hours! It constantly amazes me how the plants and animals survive, their arid adaptations making the most of every possible drop of water that falls and hanging tight until the drought-breaking rains.

The drought can have its benefits in conservation land management. Rabbit numbers plummet, and this is the best time to really go hard on rabbit control and minimise their impact when conditions improve and they… breed like rabbits! With reduced rabbit numbers and reduced native prey availability, it's also a great time to control introduced predators (foxes and feral cats). It's during these dry times that predator control is most effective.

On the back of these conditions and with the control of introduced species high on our priority list, 2018-19 provided a great platform for our program at Bon Bon. We were able to demonstrate that in an area of around 40km2, we could basically eradicate foxes with ground baiting alone for a sustained period of time. Little signs such as increased tracks of small mammals were also becoming a feature of this area – hopefully signs of recovery after a long history of grazing.

On my most recent trip to Bon Bon just last week, the road in was something I’ve never experienced. The main highway between Port Augusta and Coober Pedy was underwater!

While the majority of punters using this road were frustrated at a prolonged closure, the importance of events like this cannot be understated. Ephemeral wetlands and dry inland lakes rely on these flushes of water, as do migratory birds and even species that have never been recorded on the property before, such as Plumed Whistling Ducks turn up to make the most of lakes that are finally holding water.

All sorts of aquatic invertebrates appear from nowhere, dormant seedbanks are triggered into action and ephemeral plant species spring into life. What looked dry and parched, now a completely different landscape of colours and smells.

Mulga and Myall, two of our most widespread and important acacia species are covered in bright yellow flowers, and hopefully will set seed and recruit for the first time in many years.

Chenopods and grasses are vibrant and green with new growth, species that have been unseen for years are appearing from nowhere and the birdlife is going off!

It's these ‘boom’ times in the arid interior that lead to explosions in native fauna species such as rodents that seem to vanish in the ‘bust’ years. And it's these responses, in combination with our efforts to manage threats, that will hopefully lead to improved resilience, particularly in the face of climate change that has been predicted to increase the intensity of drought, lengthen heatwaves, alter species composition and threaten a range of species that we’re trying to preserve.

We might not be able to do anything to prevent some of these predicted changes but making the most of these boom years and doing the work we’re doing on the ground will hopefully lead to retention of groundcover for longer periods after these rainfall events, improve the capture of water across the landscape and increase the likelihood of these fragile ecosystems to sustain the lesser seen native fauna species for longer periods of time.

Fields of grass have appeared following the rains. Photo by Graeme Finlayson<br/> Fields of grass have appeared following the rains. Photo by Graeme Finlayson
Gosse's Track became a swamp, with Nardoo water ferns! Photo by Graeme Finlayson<br/> Gosse's Track became a swamp, with Nardoo water ferns! Photo by Graeme Finlayson
New lakes have appeared among the chenopod shrublands. Photo by Graeme Finlayson<br/> New lakes have appeared among the chenopod shrublands. Photo by Graeme Finlayson
Plumed Whistling Ducks have arrive. We hope they will nest. Photo by Saskia Gerhardy<br/> Plumed Whistling Ducks have arrive. We hope they will nest. Photo by Saskia Gerhardy